Kazuo Aichi, a senior Lower House member of Shinshinto, will leave the largest opposition party next week, sources said July 4.

Aichi, 59, a former chairman of Shinshinto's policy affairs council, will formally announce his exit at a news conference late July 7 and take the necessary party procedures the same day, the sources said. Aichi, who has long been critical of Shinshinto chief Ichiro Ozawa's way of managing the party, accused him on July 4 of "failing to perform his important role as party head" in a brief conversation with reporters.

Aichi's move comes less than a month after Shinshinto executive and former Prime Minister Morihiro Hosokawa left the party June 18. It was a serious blow to Ozawa's leadership.

Aichi will work remain an independent, for the time being, the sources said. He has been critical of Ozawa's move to rally conservative forces behind a proposed alliance with the ruling Liberal Democratic Party. Both he and Ozawa were formerly with the LDP.

It had been speculated that Aichi would run for governor of his home prefecture of Miyagi later this year, but he is no longer interested in that election, the sources said. He is expected to return eventually to the LDP. He once served as director general of the Environment Agency and head of the Defense Agency. He has served eight terms in the Lower House.